Asymptotic of high order (see [1]}) :
\(\forall x>0,\quad \mbox{ }I_{\nu }(x)\underset{\nu \rightarrow +\infty }{\sim }\frac{1}{\sqrt{2\pi \nu }}\left(\frac{ex}{2\nu }\right)^{\nu }\quad \mbox{ and }\quad K_{\nu }(x)\underset{\nu \rightarrow +\infty }{\sim }\sqrt{\frac{\pi }{2\nu }}\left(\frac{ex}{2\nu }\right)^{-\nu }.\) 
